Old or new, some gloves have more padding than others. Not everyone uses a heavily padded glove. I'd go to a local shop if I were you and try some on. My full-fingered mountain bike gloves aren't terribly different from my full-fingered road gloves in terms of padding. They do have some extra bits of material on the index finger though for extra grip and durability. I was taught to ride with my index fingers resting on my brakes at all times, so I like that extra bit of material. I'd otherwise wear a hole in the glove pretty fast.
As for riding a rigid mtb, I can't give you insight there as I my mtb have front suspension. You likely will have to toughen up a bit, change your grips and/or work on keeping your upper body relaxed (but not too relaxed) so that you can better absorb some of the impacts.
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher