According to Genesis, Adam was created by Gid fully grown. Hence the navel/belly button question.
Adam paraded that belly around for 930 years. He thus lived long enough to see the birth of Lamech, son of Methuselah and father of Noah, eight generations.
That’s a lot of little ones through the centuries asking why old Grandpa (to the nth power) Adam doesn’t have a belly button like we do. I would say that Adam was most likely created WITH a belly button. That way, rather than being pestered with questions from every little child that came his way, he was instead presented with good questions from well-informed older children and adults.
After I posted: - ‘Then wondered was Adam created fully grown, or as a Zygote?’
= = =
I thought about the 2nd Adam.
He WAS created as a Zygote, Holy Spirit and Mary and all that.
(Well, He always existed but this is how He came to live on earth.)
Beats questions about foreskins I guess.