Jessie, nobody knows based on the info in your post.

If you decide to proceed, monitor the space.

How about a photo of the attic space? Won't the insulation you plan to install be the same thickness? What's the advantage?

The advantage it the free flowing insulation needs to be about two inches over the beams. So using a batted insulation allow is to be even with the beams. plus the house is almost 40 years old and has original insulation. So it's due for an upgrade in insulation anyways.

Jesse, Did autocorrect affect your response?

Storing decorations in an un-conditioned space will damage them. Unless you can protect them from heat & freezing, the basement (if it's dry) is a better option. I seriously shortened the life span of a Christmas tree storing it in the garage. The needle became brittle and fell off. A new tree is easily $1,000 so take care of it.

I blocked off portions of my attic with plywood and blew in a 1000 pounds of cellulose, In another area I filled the joists with blown cellulose, covered with plywood and created a large area for storage. Works great for me. The caveat above holds - attics get hot and cold so avoid electronics or temperature-sensitive items. Blown cellulose is so much nicer to work with than fiberglass (more info if interested) - 1000 pounds took 4 hours to blow in - and you can just adjust your R-factor with depth and no groveling to the edges of the eaves.