In Christian theology, Jesus is important not because he's Jesus but because he is God on Earth, and is Christ, or the Christ -- Christ being the Anglicized version of the Latin Chrīstus and Greek Χρῑστός, or the Hebrew "Messiah" (apologies, I don't know the Hebrew character spelling). All of these words mean "anointed," that is, specially favored by God. The worship of Christ is the worship of the Lord's anointed.

Trinitarian Christians -- that is, most denominations you're probably familiar with -- believe that Jesus is one of three aspects of God, the others being God himself and the Holy Spirit, and that these are one continuous being with distinct aspects. What they're worshiping is not just Jesus, but the entirety of the Trinity, and they generally believe that Jesus was both fully God as he existed on earth, and also fully human.

The Nicene Creed -- which has been amended both officially and unofficially from its first recorded writing in the fourth century -- is one of the foundational texts of trinitarian Christian belief. It goes like this (some versions are a little different):

I believe in one God,

the Father almighty,

maker of heaven and earth,

of all things visible and invisible.

I believe in one Lord Jesus Christ,

the Only Begotten Son of God,

born of the Father before all ages.

God from God, Light from Light,

true God from true God,

begotten, not made, consubstantial with the Father;

through him all things were made.

For us men and for our salvation

he came down from heaven,

and by the Holy Spirit was incarnate of the Virgin Mary,

and became man.

For our sake he was crucified under Pontius Pilate,

he suffered death and was buried,

and rose again on the third day

in accordance with the Scriptures.

He ascended into heaven

and is seated at the right hand of the Father.

He will come again in glory

to judge the living and the dead

and his kingdom will have no end.

I believe in the Holy Spirit, the Lord, the giver of life,

who proceeds from the Father and the Son,

who with the Father and the Son is adored and glorified,

who has spoken through the prophets.

I believe in one, holy, catholic and apostolic Church.

I confess one Baptism for the forgiveness of sins

and I look forward to the resurrection of the dead

and the life of the world to come. Amen.

Again, this version is different in some churches -- the Eastern Orthodox church rejects the addition of "and the Son" to the line "who proceeds from the Father and the Son" -- but it gives you an idea of the agreed-upon basis for worshiping Christ, and how that's different from Jesus per se. The shorter Apostles Creed is used in many churches as well as or instead of the Nicene and its versions.