Analogy; In A River

You can be in the river going against the stream. (not good).

You can stop fighting it and go with the flow (better) but without a rudder (not good)

Or stop fighting it, go with the flow and use a rudder to navigate away from danger and still go where you want.

This is how I look at it. Yes let go to an extent but you have to act to navigate. Know you are moving in the right direction (river) and you make necessary changes to create what you need (use of rudder) to do new things and avoid shortcomings (rocks in the river)

So it's a balance of letting go when necessary and adjusting direction when needed.

Inspired action is sometimes needed; no doubt about it!

If the situation is life threatening or harmful you must respond. However, if the situation involves the advancement of another persons lesson in life, like responsibility, speak your mind, and leave it alone. The laws are connected to one's intention. Something that is meant to be is what you are doing right now. You are what you seek. Try not to extend that power too far from yourself. Your focus is from the inside out. Then you will get feedback, and then you respond. Stay local to you and minimize your extension.

The Knights of Alchemy.

You do not leave things alone when letting go. You put them into motion and leave them with a confidence they will bring you success. It is like shooting an arrow. You make a precise shot and turn around before the arrow hits the target, knowing that it will happen.

the discussion of manifesting/creating vs. letting go, to obtain (as contradictory as the last one is).

I never thought of these two as "vs" . More like two steps in Ask,accept and receive.
Asking Is the manifesting/creating and letting go is the accepting.

There are times where I had to step up and take control and if I had not, the consequences would be hard

As far as stepping up it is as The Knights Alchemy says; Something that is meant to be is what you are doing right now. Stepping up is you being present and very much in the now. A good thing.
Murphy's laws are something to laugh about and show us resistance.If you want them to work they will.
Like attracts like.

If these are at work in a specific situation, we must take control....that is my opinion.

If you truly are in control it is given to you and not taken. And that is to even to say the you give yourself permission to have control, i.e. :use of the rudder(Nice one Michael)
peace

If you let your mind go, and not attend to your thoughts, chaos is sure to be evident in your life. If you take control of your thoughts and not obsess on negative thoughts, but eliminate them appropriately, and replace them with positive thoughts, then you have control of how you respond to life situations, and then you have order in your life. You will attract good things instead of randomly attracting whatever your vibration attracts. Control your vibration and your thoughts, control your life.

I agree we do need to let go of this FAITH in Murphy's Law. It is an hindrance to our FAITH in God and that everything will be cool if we do not worry about it.

Peter is an example of this belief in Murphy's Law he at first believed that through Christ he too could walk on water. However his belief that something will go wrong caused him to drop into the sea like a rock after he was just walking toward Jesus he took his gaze away from Jesus and sunk.

Keep your eyes on Jesus and give up this Murphy's Law in fact apply Morty's Law "Whenever possible something is going to happen that will change everything for the better."