how did people in Europe in the 16th century believe the natives had originally gotten to the New world? Did people in 16th century Europe believe all humans were from the old world originally?

by grapp
intangible-tangerine

Quite a bit later than the period you're specifically asking about, but there have been numerous theories from the 17th c. onwards that linked Native Americans and other 'discovered' peoples to the ten 'lost' tribes of Israel. An early proponent of this theory was the Portguese Jewish traveller Aharon Levi