How would you react?

I would think “Wow, different people in a boat. Wonder what they want.” I am pretty sure they knew what boats were if they lived on the coast.

I would hide myself in the bushes and observe them and study them from the distance first.

I would think, “Man, those guys are really in for it. The local slave traders that captured me and the rest of my tribe are real bad-asses.”

Of course, I’d be wrong. Probably wouldn’t occur to me that the guys on the ships would be even worse.

I would track them after they land on.