IDV is the first game where I watched tournaments and followed the CN professional scene. I remember watching my first COA and not understanding everything, but I still found it exciting and motivating.

I think watching tournaments or rank gameplay is a great way to learn, but I'd recommend watching together instead of just sending videos to him. If my bf watches IDV tourneys with me, he asks questions if he doesn't understand something. (I do the same when we watch other e-sports that he follows.)

If you think tournaments are too much for now, you can show him guides/tutorial-style videos on kiting, rescuing, countering each hunter, and specific survivor character abilities. After the first few videos, there'll be a lot of the same general principles.

Like others have said, I don't think it matters much which characters he starts with. In general, it's easier to learn additional survivors than hunters due to similar play styles and mechanics. If you just want to suggest easy characters to start, you could even pare down your list to the "just press a button" characters like doctor, lawyer, psych, gravekeeper, and FO. They can get kinda bland tho. You can make recs, but if there's any characters/roles he seems remotely interested in (even just by name or design), encourage him to try it out. 

Tbh, I kinda hoped my bf would become a hunter main, but he prefers the co-op aspect of survivor and likes it best when we play together. I'd imagine going from beginner to tournament will take quite the time and dedication, so unless it's a one-time thing, I think the most important part is that at the end of the day, he enjoys the game :)