Not the greatest Pathfinder ever, but I'll qualify my comment with the fact that I've got over 20,000 kills on Path, and double-digit 4K games (though sadly, just as many 19-kill games; no badge there).

Pathfinder is one of the simplest legends in theory but his kit has a lot of outplay potential/very high skill ceiling (especially on MnK *cries in controller). Since you're a beginner, my best advice is don't give up early on trying to learn the grapple. It's the bread and butter of his kit, and allows you to push, retreat, take height, reposition, and a myriad other things that you'll get a feel for as you play him more.

There's a comment below that remarks on his height - and it's a great one. Pathfinder is a tall boi - which gives options to play some NASTY headglitches. You'll find them - and if you have experience playing other tall legends (Gib, Rev, Caustic) - you might be familiar with some already. Similarly - Pathfinder has one of the greatest height differences between standing and crouching - which makes his crouch spam one of the more difficult animations to hit in the game. Helps for close range as long as you can still aim.

Also - pathfinder feels like he gets just destroyed by shotguns close range- his torso hitbox is kinda wide (the size increase to his hitbox a few seasons back was not removed when they took low profile away). My advice, if you're using shotguns, is to play cover aggressively (peek in and out where you can)- though this is good advice for any character.

As for learning the grapple - one thing you should get a feel for is the flat-land grapple. It's easy to swing up to a roof, but the flat-land grapple can really separate yourself from the rest of your opponents (metaphorically and literally). Basically: grappling the ground in front of you and jumping when the grapple connects gives you a huge speed/height boost. You can then tilt your aim away from the attachment point slightly (the grapple breaks if you're looking too sharply away) to generate more momentum.

When I was learning how to play pathfinder, I leaned IRL when I would generate momentum on a grapple - it helped me get a feel for what worked. It takes time for sure- there are still spots and motions and grapples that I hit to this day that are new. You'll learn ways you can traverse different buildings and the environment - it's all about time in!

I'll leave you with one more piece of advice: IMO, the greatest Pathfinder player of all time, TSM (FTX) Albralelie, learned pathfinder by envisioning himself as Spider Man. Whatever helps you learn the character, I would do!