Asalamuallaikum.
At first, please forgive me if I make a mistake in my post, because I am not scholar but ordinary ummah.
Prophet Adam (peace be upon him) was tall as palm tree when he was in heaven. However, after he came down to the earth, Allah subhanawata'ala made him shorter because his height was too tall for living in earth.
We can imagine if in this modern day 5 billions people who tall as palm tree live together on earth. There's no enough food for eat, there's no enough space for living.
Goliath (Djaloot). Some manuscripts described he was more than 3 metres or 290 centimetres or 246 centimetres. But few manuscripts described Goliath's height was 208 centimetres, same as modern basketball player.
Maximinus Thrax, caesar of Rome. Many building from ancient Rome are still stand. And we can see, people's height in ancient Rome periode are normal. I don't know about skeleton that descibed as Maximinus Thrax's skeleton. Maybe that is not his skeleton.
There are some huge graves in Syria. But I think that is not because persons who burried in those grave were huge, but because those are great persons (VIP) grave. And those huge grave are for show their greatness.
There are many thousands years old mummy. And their size are same as modern human.