creeper gear w is it used for

Yes

If you roto-till in creeper gear, be sure to get paid by the hour!  Low in creeper on my tractor is 1/10 of a mph.

A better use:  I cut quite a few trees up to 18″ caliper, and leave the 6″ – 8″ high stumps alone for about a year so the part you see abve ground gets soft and pithy.  I then take them out ( or rip off any part above ground ) with a potato plow on the 3  point hitch.

I just drop the plow behind the sump, with the plow point centered in the middle of the back of the stump, put the tranny in 4WD, and then shift into creeper, low side, first gear. Usually, the stump comes right out.  On a really tough one, I lock up the rear axle.  If the stump doesn't all come out, you can  make several passes through the stump and tear off any wood sticking up high enough for the mower to find-do a little dirt work and seed, and you never know the stump was there.

BTW:  284 Jinma, 12 speeds forward, 4 reverse

Bob