You are transported into the Marvel Cinematic Universe, at the most recent era (I guess as of the events of Eternals and Hawkeye as of this post, No Way Home is coming out shortly). You have all the knowledge you currently have about the MCU and gain one superpower granted by the mischevious cosmic being that uprooted you from your home dimension and placed you into the MCU. You get to choose the superpower, but your access to your home dimension is forever lost.
1) What superpower (remember, only one) do you choose?
a)You cannot choose powers like "Magic", "Reality Control", or "Quantum Energy Manipulation" or anything that gives you a vast swath of abilities where you are essentially god-like, but something that gives you a significant array of potency (Telekinesis, Gravity Control, or Weather Manipulation) are certainly possible. You can practice and gain more control of your power over time, but start off as a novice.
b) If minor abilites that that typically go along with the main power (Weather Manipulation and minor resistance to heat and cold, or Fire Manipulation and immunity to Fire) those can be assumed to be granted, but they must be minor (not, for example: Flight and Super-Strength)
2) What do you do when you get to the MCU? (Meddle in events, live quietly and surreptitously with your power, try to parley your movie and TV gained knowledge into an advantage?)