Code looks OK although mixing direct changes to transform position and physics (add force) isn't always best (can cause odd behaviour when in collision and this might be the issue - object is in collision with surface). You might want to consider applying forces on the x axis the same way you are jumping. So not part of jump code, but similar apply force in x direction in "FixedUpdate" (not update as physics happier with fixed frame periods)
That said, it's all about scale. Your move code means move at max 10 units per second depending upon horizontal axis deflection (delta Time is fraction of second per frame). So, if the scale of your scene is really big, a change in move speed might be unnoticeable.
↧