"Assumed" and "ascended" are two different words. Jesus ascended to heaven by his own power. Mary did not.
I will never understand why non-Catholic Christians object to the Assumption of Mary, since many of them think they will all be assumed into heaven in an instant at some point in the future (they call it "the rapture").
I don't find that in the Bible, but I do find Revelation chapter 12, which speaks of a woman who is the "Ark of God's Covenant".
The Greeks speak of the Domition of Mary. But the teaching is the same. At the end of her life she was brought to heaven to stand by the side of her son. A church dedicated to the Domition is in the Holy Land and it dates to the 4th Century. But some Protestants think that the dogma was something made up by Pius XII in 1950.