Your form is bad. In my opinion, dumbbells are better for getting a feel for the cues, but if you are going to stick to the bar:

Move your grip in. You should be grabbing the bar just outside of your shoulders, not to the rings. If gripping it just outside of your shoulders feels too long, move your hands in to shoulder width and then work on moving the grip out a little by little. Don’t fight your body mechanics, it’s an express ticket to getting an injury.

Make sure you actually have your arms/elbows locked at a 45 degree angle, and your lats locked (lay flat somewhere with your arms up and focus on squeezing the sides of your upper back down to get a feel for this- plenty of YouTube videos cover it) with your back flat on the bench. A slight arch is ok, but don’t over do it, and at your level I would focus on keeping your back flat anyway.

Feet flat on the floor and brace your core. By brace your core, I mean breathe in deep to your stomach and pretend like someone is going to punch you in the gut.

When you are getting the bar out of the rack, you are driving it out. Think of your body as one system. The core braces, the legs drive, the force goes into the bar to lift it, and the counter-force from the weight of the bar keeps you pinned to the bench.