Any suggestions on how to fix holes in jeans without sewing or even something to wear underneath the jeans and leave the holes as is.?

If the crotch inseam is going there's really no satisfactory way to repair it. Those iron patches work great on the knees, not so much so on crotch area where the fabric wrinkles a lot.

Jeans with reinforced seams on the OUTSIDE of the leg instead of the inseam seem to do better, but they will eventually wear thin in the crotch too. If you insist on wearing jeans it's worth the trouble to either buy or have altered your jeans so they have a diamond crotch gusset. If you know any serious old-school bikers they usually know where to source these.

If you're doing manual work jeans aren't what they're cracked up to be. Get yourself to an army surplus store and get combats, real ones, not the fashion kind. They hold up really well, you will get years out of a single pair. Get the black ones, they look smarter.

iron on denim patches, available online or at most fabric stores. simple.

put a denim colored patch on the inside of the jeans, it will iron on. Ive done this before, cant remember where i got it

Iron-on patches

Buy pants which fit.

Your job isn't hard on your clothing, you just bought ones which don't fit you well or are you going to claim that your job wears on your crotch?

This is just the material being stressed in the wrong way when you're active.

Repairs; a stapler. Wear flame-proof metal mesh underwear.

Maybe glue some fabric on top it. Looks cooL!

Some sexy sheer stockings underneath would work. That's what you want to do anyway.

They sell iron on denim patches. It doesn't get any easier than that.

shoe glue and some fabric patches will work