Have you tried watching any brackeys or blackthornprod tutorials on the subject, because they are the unity masters. Although I would recommend them first, here is what I used when making Rb2d physics (I had some issues of the player rotating when they hit an edge, which is the only reason I wouldn’t recommend this, but maybe you can solve this).
I first used Input.GetAxis to find out which key the player was pressing, and then multiplied this by a variable called PlayerSpeed, and I would set the result to be a variable called Movement. This then went into a Vector2, as well as Y, calculated by Rigidbody2d.GetVelocity. This then was used to set player velocity. I did this in Bolt, so you might have to modify some things for code, or change the physics a bit, but this led to quite snappy movement. I hope this helps, at least as a base