These "inner sleeves" or "envelopes" are meant to provide an extra layer of protection for the record from the comparatively scratchy cardboard jacket. Any new record you buy will already have an inner sleeve. It may or may not have a hole in the middle like these. Many inner sleeves are printed with song lyrics, or credits, or artwork. If you already have an inner sleeve, there is no need to add an extra one. They are floppy because they go between the record and the jacket, so they don't need to have their own structure. They can sometimes bunch up going in and out of the jacket, so many people reorient them so the record can be put into both the envelope and the jacket at the same time.
The main use for the packet of sleeves you have is to replace the inner sleeves for used vinyl purchases. Since the inner sleeves are made of paper, they tend to wear out much more quickly than the vinyl or than the cardboard jacket, and therefore have to be replaced.
There's no need to take the record out of the original packaging unless that is worn or damaged. Serious collectors add an additional layer of protection in the form of a clear plastic "outer sleeve" that goes over the cardboard jacket. As an alternative to this, many people will keep the original plastic cling wrap intact as long as possible.