One idea is they may sell many of the serfs as slaves to the people down in Africa in exchange for food and such which could lead to new ideas and such reaching further down into Africa.
I trust you're aware of why Europeans didn't start trying to live in most of Africa until the 19th century?
(I'm also not sure how big market there was for short-lived slaves there at the time, or if they had any
meaningful food surplus to trade.)
Unless you mean North Africa, in which case the question is "Didn't they get decimated by the Black
Plague just like Europe and the Middle East?". They're not very likely to have a bigger demand for slaves
or any food surplus to trade in a world where they didn't get the black plague either. And if they did get
it...
Have a bunch of big ships dump the poor peasants near the shores of Newfoundland or such while they go back home to deal with whatever issues they have back at home.
It might be the connotations of the verb "dump" (not to mention of the phrase "dump near the shore"*),
but I'm not sure that survival, followed by the spread of knowledge and technology to the Native
Americans would follow. The way you phrase it Europe wouldn't exactly send their best and most
well-equipped (and if they did, they'd bring people to keep an eye on them and stay in contact).
*If you're going to do that, why bother going all the way to Newfoundland?