Groove Monkey free package has some decent loops. I use them some times in Reaper. The folder names and file names give good clues to what they are including, and estimated tempo they might be used for.
I also created a folder that holds all of the Power Tracks midi drum files, the one used for "Load Scrap". These work well for starters but lack fills and rolls.
Here's a short cut you might use. Think of a blues song that is similar to the one you are creating. Download a free midi file from the internet. Drag it into your DAW. Mute or delete unwanted tracks. Make edits in the Piano Roll/Midi Editor. Sometimes I use a midi controller keyboard to manually record my midi fills and other parts onto a new track. Then I mute the adjacent sections on the original track until I feel confident to cut them out and paste in my fills and other parts. Many of the midi files I find for free sound rather cheezy when played back through Windows Media player (computer synth) but when played back using my hardware synth or even SI Drums that came with CakeWalk they come alive better depending on how the file was made. Keep in mind that SI drums is not a full GM/GM2 or GS synth. So it does not have things like shakers and cowbells and many others voices. If those instruments are in the original file you will see them but not hear them. If I feel they are important I copy just those onto another track and choose a separate synth, TTS-1 or hardware for example, just for those instruments.
Or, load a similar blues song .wav file into Band In A Box's Audio Chord Wizard. Let it interpret the chords which lays out the song in BIAB chord sheet. Mute all instruments except for drums. Choose a BIAB blues style, midi or Real Drum with an accompanying midi style. Place style change markers where you want drum rolls. Export to you DAW...
Well, there's some ideas anyhow.

Does the noise in your head bother me ?