Is Christianity based on older myths?

[Minimalist]

Let's not forget Justin Martyr:

CHAPTER XXI -- ANALOGIES TO THE HISTORY OF CHRIST.

And when we say also that the Word, who is the first-birth of God, was produced without sexual union, and that He, Jesus Christ, our Teacher, was crucified and died, and rose again, and ascended into heaven, we propound nothing different from what you believe regarding those whom you esteem sons of Jupiter.

First Apology c 160