Building an AR-15 is a lot less daunting than it appears to a new person.
Just like anything - the first time you constantly check between your work and Google (like me haha!) - but you'll quickly realize it is nothing more than legos for adults.
Just make sure you have the proper tools - like AR Wrenches. You can buy universal ones that will handle the barrel, barrel nut (if needed), buffer tube, butt stock, etc. etc. For $30.00 or less.