Around here a lot of "hiking trails" are black diamond MTB trails and some are even red, so you can't really classify hiking trails as easy.

To ease into riding check out Trailforks or MTB Project. Start with purple and green trails. Purple is usually gravel roads, but sometimes can be rougher two-track keep trails and the like.

I ride at least a couple times a year on a '91 rigid MTB. I like the challenge. Riding the same trails on full suspension is definitely faster and requires less attention.

I also ride gravel on a road bike with 30mm tires a lot. Sometimes I take the XC hardtail on gravel. Last ride I did was a mix of blue green and black trails on the rigid plus bike. All fun.