That's funny, I feel the opposite about Deadlock! There's not really a MOBA first person shooter that is out there, particularly one with such an in depth movement system that is fairly ubiquitous for each character. It does have a skill ceiling, but I would say for casual play, especially starting out, it's mostly about being patient brick wall and playing the denial game to force mistakes that you can punish.
It's effectively a first person MOBA with characters that you might see in Paladins. It feels really good, but it is intense for sure -- my biggest issue is map navigation and learning it as a whole. But I also really like technical gameplay, one of my favorite games is Smash Bros. Melee so this is just an extension of that love.
I would say if you wanted to give it a shot (if you haven't already) give each character a shot in the training ground. Get a small feel for their abilities and it'll help you get a sense of not only what feels fun for you, but also what to expect from the opponents! Edit: I had read your comment over again after I posted of course and I had forgotten that you did go into the testing ground. Sorry! lol. End edit. And for items, that's a bit harder, I personally don't care much and just go by passives that sound helpful. Just click once though, double clicking will buy and then sell the item.
Which, in a way is a testament to my first paragraph. Patience is key ;)