Are mattel he-man toys from the 80s safe to play with?

Depends by what you mean "safe"

If you mean will playing with them ruin the collector value, it depends on the condition they are in and how rare each figure is. Certainly it will sharply decrease the value if you remove it from its box, but if it was in poor shape to begin with, chances are its not worth a whole lot and playing with it won't make it lose any more value.

If you mean will it hurt you, it depends on who is playing with them. Naturally you're going to want to give the Action Figures to kids who won't choke on them or anything, but chances are there's nothing especially dangerous about them when compared to modern action figures. Common sense rules still apply.