Captain America/Black Panther speeds (60-80mph+) would be a useful level of speed even more so if (unlike cap/BP) this is just their jog speed not sprint speed. Once you get in the hundreds you are talking incredible speeds like just imagine going 80mph on the interstate and seeing a person fly by at say 200mph. It would be insane much less 500mph.
Once you get into speeds high enough to outrun bullets you are talking potentially 3000fps+ (at least 1500fps). At ~3200fps you would be as fast as the fastest air breathing manned aircraft in the world (SR-71).
If you want to leave bullets in the dust then you are talking up around Mach 10 (~7,700mph) which would put you over 2X the muzzle velocity of most rounds and faster than the speed of the experimental unmanned hypersonic scramjet the X-43A (7,307mph).
To really make a joke of bullets jump up to 20,000mph. You are now exceeding the speed of a space shuttle launching into space and over 6X the speed of most bullets.
Now to shorten the numerous steps I could take working my way up I’ll just end on this at 1% of the speed of light you are at ~6.7 million mph at this speed you are going ~1860 miles per second you could travel the circumference of the earth in ~14 seconds (ignoring obstacle, just in terms of distance) or for a completely unrealistic example if a sniper took a 1000yd (3000ft) shot and the bullet traveled 3000fps the entire way to its target you could be in San Antonio, Texas and the shot being taken in NYC and if you left at the same time the trigger was pulled you could have moved the target over 30miles away before the bullet got there (assuming you used a car route to get there + ignoring traffic + instant acceleration....etc.). The distance you could go in a blink of an eye (1/10 of a second) would be 186 miles approximately.
It is due to the mathematical reality of things like that last one that is why it is ridiculous that anyone who isn’t also at speedster levels could hit a “light speed capable” Flash not to mention how ridiculous that anyone who didn’t have significant durability could stand up to punches with that much energy behind them just consider how light a bullet is compared to a fist and it is moving considerably slower than Flash’s fist. In reality it would take major restraint not to kill anybody and collateral damage would be significant idek what would happen to the surfaces you ran on.