2 hours Connection T5 Heathrow

Will you have checked bags? If not, then you should be fine, provided that your inbound flight is on time. Just follow the signs to connections (not arrivals). You won't have to go through UK immigration or customs, but you will have to go through security (as all connecting passengers at Heathrow do). You can make things a bit easier if you can (1) have your connecting boarding pass in hand when you arrive (which means printing it out before you leave home), and (2) make sure that if you've picked up any water bottles or other liquids during your first flight, you empty them, discard them, or pack them in your 3-1-1 bag prior to security.

If you do have checked bags, then you'll likely have to go through immigration, reclaim your bags, go through customs, recheck them, and re-enter the terminal. Two hours might not be enough time to do all that.

I usually get from my T5 landing back into the departures terminal of T5 in 45 minutes. When on time, etc. I don't know that I've ever taken more than one hour. Keep in mind, time is needed to get to your departure gate in addition. However, based on my experience of many years as T5 is my airport of choice in Europe, you should have ample time assuming there is no delay. That being said, I usually allow 2 1/2 to 3 hours, which affords me time to eat and browse or accommodate a delay.

Are you sure they are separate tickets? If so, would BA combine them so you don't have to worry regardless of timing?

I am not clear about 'separate ticket'. If you booked BA from USA to Munich, via LHR, then your bags should be checked through to Munich and you don't have to touch them till you arrive in Munich.

If so, although one is dozy after a transatlantic flight, it's important not to go with the crowd following the yellow signs to arrivals, but to look for the purple signs to flight connections.

If you booked two separate flights and your bags are not checked all the way to Munich, then 2 hours is not enough in normal circumstances to queue through immigration, collect your bags, go to departures and check into your Munich flight. Check in will close 45 mins before your Munich departure which means you have only 1h15 to depart the aircraft, get to and through immigration and customs and get to check-in

If the plane arrives early at LHR you may make it, but it'll be tight.

You can put your flight numbers here for info on connections
https://www.heathrow.com/connecting-flights

You need to present yourself to security no later than 35 minutes before your flight time, otherwise you are out of time.

If you land at a satellite (ie 5B or C) and also depart from a satellite then clear security at your departure satellite which saves a lot of time. If either flight operates to/from the main building (5A) then you have to clear security there, along with originating passengers. Unfortunately you do not know this until you land and check where you are and the departure screen.

As you have already bought your ticket check whether it is a 'Plus' fare or not. If it is you can reschedule on the day for no cost providing it is 60 mins before your booked flight. If not you have to pay the fare difference at least. This at least helps against minor delays. (If you bought a fare that does not include hold baggage, then this is not a Plus fare.)

We try to leave 3 hours between flights when possible. As long as your flight arrives on time, and if you don’t pull up to the terminal the busses are waiting, you should be ok. Last December, since there were few busses to take us to the terminal, it took my wife and I 30 minutes to get off the plane and to the terminal. Then another 5 minutes to get to immigration (LHR was our final destination). Add that time to the 35 minutes before departure that you need to be at your departure gate, and there’s little room remaining if something goes wrong. Then again, maybe your plane will pull right up to the terminal and you de-plane in 10 minutes.