If you suck at FPS I would say that it's certainly a good reason to leave and come back when you've brushed up on your skills. This game does not offer a very good training environment. There are too many things happening in the main game that are secondary to the gunplay itself and the shooting range doesn't offer any goals or fight back.
You will learn at a much slower rate by grinding out poor matches back to back. To perform averagely and make the most out of this game on PC you are better off going to one of the other prominent competitive shooters to work on your core skills; aiming habits, positioning, mobility, reading your opponents intentions while hiding your own. No amount of fact checking or map knowledge will fill in these gaps for you.
CSGO would be the other F2P game that I would recommend for fine-tuning the fundamentals. Not necessarily the core 5v5 defusal matches. You have a massive pool of community deathmatch servers with people just like yourself who are focusing on improving rather than watching their k/d. And people have constructed customisable shooting ranges which can easily be found through the Steam Workshop. You can tailor the challenge of these to keep up with your current level of skill.
But also do use the wealth of videos out there to figure out HOW you should be training. The Counter-Strike community has been around much longer than CSGO itself and they have been extremely thorough in that regard.
This is all just my recommendation of course. You should be able to grasp the quirks of Apex Legends far more smoothly when you return if you decide to go this way.