Depending on your culture and your time your answer might be different. 
Some might say Ben Franklin, Martin Luther King, Alexander the Great, Julius Ceaser, or Mother Teresa. 

Yet the one person who has impacted humanity the most is Jesus Christ.  He is talked about more than anyone else ever was, preached about every week.  The Bible has been the best-selling book for years.  No other book outsells the Bible.  Other books that make the top selling lists are about Jesus Christ, Christianity and how to follow him. 

Holidays include, Christmas is to celebrate his birth, Easter is to celebrate his resurrection, Passover matters, because he was the Passover lamb, and these holidays are celebrated in many different countries and are not just a national day to celebrate someone within a nation’s culture.

Yet there are still some people who have not heard of him,
nor do they understand how or why he is the Messiah.

We will talk about why this is important.

Why you need to know this – and even if you choose to reject it, at least you knew it first. 

You see God gave us a right to choose.  Free choice, to love Him or to ignore Him.

He did not want to force us to love him, because that is not genuine love.

He wanted people to choose to love him.
He cherishes those who choose to love him, not just say ‘luv u’ yet have not heart behind it and do not really mean it.  He wants people to love him with all their hearts, their minds, their souls and their bodies.  This commandment was first given in Deuteronomy after giving the 10 commandments in chapter 5, Moses tells the people in Chapter 6:4 (Read verse)

WHAT IF?
What if before you can get into eternal paradise, God asks you how well did you love?
How well did you love others, yourself, my son Jesus, the Holy Spirit and Me as God of the Universe?
Will your words matter, or what God saw you do in the secret places of your heart?

Do you think God will skip over you, and not judge you according to the laws of the universe?
A child (who does not know the law of gravity) will jump up return back to the ground, because gravity is a universal law, even if the child does not understand gravity.

Eternity exists, Jesus talks about it.  Heaven and Hell are out there within this Universe, and Jesus DID come to save people from their sins.  We all want to be saved, but not usually from our sins.  Some people like what they do wrong and do not want to change.  That is their free will.
Yet there are universal consequences for the choices we make.
Just as Jesus made choices and the consequences from those choices brought universal redemption, salvation, acceptance, and love for all who choose to believe in Jesus as the only Son of God.

Although we will talk mainly about what is written in Matthew, Mark, Luke, and John.  There is so much more within the whole Bible.  It talks about how before the earth was created, God created the Heavens, and all that was within it.

The heavenly beings worshiped Him. Then pride came to one third of the angles.  Satan and all the angles under him, rebelled against God.  The Devil (Satan) thought he was greater than God.  He did not need God.  He did not need to worship God.  Even though Satan perceived himself as greater than God, he was kicked out of Heaven by God. 

In the beginning when God created the earth and all that is in it.  God also created people, Adam and then Eve from one of Adam’s ribs.  God created people because He wanted to have someone choose to love God and be His friend. 

Satan came through a serpent (or as a snake) and caused Adam and Eve to sin.  Which has brought death to our world, and has separated us from God.  Before they sinned, they walked with God.  After they sin, the Bible records how they hid from God.  We as people have been trying to hide our sin and or ourselves from God ever since.  (Yet He still knows.)

Their sin effected all of everyone. 
Now humanity has the universal curse of sin, physical death.
There is nothing people can do to break that curse.  In the Old Testament, God gave instructions as to what people were to sacrifice after committing sins, or what the price was to pay. 
The consequences of their choices.

Some people try to deny God, and refuse to seek him.  They try to fill their loneliness with another person, with hobbies, with things, with work, with food, with drugs, with social media, and or other addictive substances.   Yet deep down they do not find true contentment within their souls, and they are never truly happy.

Sin separates us from God.  Yet we can still talk to God.  We can even feel God’s love, His healings, and His blessings if we do not have a personal relationship with Him.  Most people do not realize God was working in their lives until later and they look back at what was going on in their lives.  But those who choose to develop a personal relationship with Him, enjoy it even more.

The only way to be permanently redeemed from the curse of sin was that someone needed to pay the sacrifice for sin, a Passover lamb.  Then we could have an eternal personal relationship with God as God had intended before the Fall of Man (heaven).  Thus protecting us so we do not receive the same eternal consequence as what they Fallen Angles will be receiving (hell).

We are all perfectly imperfect.
Yet only a perfect person could be a perfect sacrifice.  Prophets in the Old Testament, spoke of the Messiah, who would be the Christ and how He would bridge the gap sin created between God and man.  If you want to have the hopes of living eternity in Heaven, then you need to understand the spiritual laws God established for ALL to be judged by. 

Remember God gave humans a freedom to choose.  We also need to respect people do have the right to accept or reject God’s truth.  It does not mean they are better than God.  Nor that God’s final judgement will not happen.  It just means they have the right to make their own choices.

Jesus did come from a family tree that had some obviously imperfect people.  Jesus also had honorable men and women in his family tree, they were also imperfect, yet beyond their imperfections they loved and obeyed God.  They respected Him, and honored Him.  God saw was within their hearts, and even when they made mistakes (some more than others) God saw whose heart still meant to do well by God. 

There are many people now, and there have been many people who have already lived, yet our lives are but a short breath and then we are gone.  God remains before us and after us, He is always looking for someone to be His Friend.  But He is Holy.  The only way to have a personal relationship of depth that will last beyond this present life, is to understand the purpose of God’s plan for your redemption.  To understand Why and What Jesus did, so one day you can also help someone else learn God’s Plan for their redemption.