Most Helpful Guy
After a year apart, at least that is the impression I get. It sounds like he is trying to bridge the gap between the two of you. At this point, with the occasional comment/like or asking how you are. I don't see it as a big deal. He wants to be friends.
Of course there is a possibility he wants to get back together. But I feel there is not enough there to say that is his intention.
Lets face it whether the two of you end up as friends, or in a relationship, or stay as you are. You are the one in control of those decisions. What happens is completely out of his hands.
You can block him (if you can on instagram I don't know). Ignore him. Or have a bit of communication. It's up to you. If you do communicate, you will likely figure out what he wants soon enough.