Bluetooth earphones? or Wired earphones? connected to the Mac? (but you say you are not using aggregate I/O as the playback engine?)
- or Wired earphones connected to the Microphone output socket?
What *exactly* are you doing? We cannot guess.
And the input level in dbFS measured on the input track... if your input is clipping then the meter that will show that is the track input meter when you are in pre fader mode. Which is why I am asking for that.
You start by not clipping on the input and then not clipping output is just all software, settings in Pro Tools. Pull the track level down by adjusting it's fader gain, clip gain, plugin settings etc. but if you are a beginner you should probably not be tracking with plugins/or playing back through them until you get this sorted out. You control the level/perceived volume of the track by adjusting the track fader (which should not make any change to the meter on the track, as you should be in pre-fader metering while tracking) and a master fader that you can put on the output. Your sessions while working stuff out should be super simple, one or two tracks and a master fader track as well, no plugins.
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The loud noise is feedback. Totally expected when you put mics in front of monitors playing back the mic signal. You might make much faster progress if you read a book on basic audio engineering. Like
https://www.amazon.com/Recording-Eng.../dp/B01MY9ZP2W or take a course like
https://www.artandscienceofsound.com.