Is there an explanation for this habit?

It could be something he learnt as a foal as a sort of comfort, like a baby blanket but in rope form. At least he's not chewing wood and fencing. It could also be that it feels spongy and weird in his mouth so it's just interesting, like if you chew a pen.

It doesn't strike me as a bad habit if it's only the ropes and nothing else. Unless it becomes a problem, I would just leave him.

Licking hands is about salt and whatever you had on your hands before, I doubt it's connected.

The horse I ride was bottle fed as a foal (he's a twin) and he is INSANELY mouthy. He mouths your hand, your shirt, pants, the reins (his favorite), the whip, the saddle, water bottles, tarp, water rafts - pretty much anything you put around him. We attribute this to his being bottle fed as a foal and whenever he does it we usually push him away (he can get quite destructive). He's got a dangling salt lick as well but seems to prefer his reins. What he does it lick, lick, lick, grab with lips, mouth, bite. With his reins he will just bite them.

Another horse I know is mouthy as well, bites trees and his lead rope, too. I think it's just because of his hot personality and boredom mixing together.

So to answer your question; boredom or a previous experience or personality could be the cause. Nothing horrible to me. :)

Horses don't have hands, so they use their mouths to explore. Young horses especially, particularly young male horses, can be very oral. They will chew on ropes out of boredom or for the fun of it. The older they get, the less inclined they are to do it.

Generally, it's not a good idea to let a horse chew on anything not meant for chewing. There's always a chance he could ingest some of the material. Also, depending on the quality of rope and if he's tied up with it, he could chew through it and get loose.

There could be a lot of different explanations. He could be bored or hungry but it sounds as if he has plenty to keep busy with and that you take good care of him so my best answer would be that he's just really mouthy and playful. Some horses love jolly balls and others just don't. Every horse has different things that they like to play with and maybe he just really likes the feeling of chewing on ropes. Does he eat fine? Because he could have teeth problems and the soft ropes might feel good on his sore teeth. If not, then maybe he just is very playful. It's important not to let this go to boring but as long as you don't mind it it doesn't seem like a huge problem. Pretty cute, really! Sorry this wasn't more helpful! Sounds like you have quite a character on your hands! Glad to hear that you at least like his unique playing habits. :)

boredom

anxiety

boredom.

clearly he doesn't feel like you do much with him. so he has to entertain himself.

horses like this are very intelligent and get bored easily.

he needs more productive exercise.

think: trail obstacles.

Seems normal just wants to play with it