So I have recently stumbled across a super cute mule. He is just a baby at 5 months and the horse breed in him is QH. Momma was a donkey.
Did the owners say this? They told you the mother was a donkey?
If so, this is actually not a mule, at all. This is a Hinny. A mule is a mare bred to a jack, or stallion-donkey. A Jenny, or mare-donkey, bred to a stallion is a hinny. I know close to nothing about Hinnys, but I can tell you a bit about Mules! :) If this is in fact one - If the owners said the mother was a donkey, it's a hinny. If they just said its a mule, and you assume the mother was a donkey, it was actually the sire that was a jack :) Extremely common confusion, no shame.
Anyway, I think that you would LOVE having a mule!! They are so smart, and so willing once you get them going. Most actually really love jumping, as previously stated. But I would be slightly cautious - In riding/showing the mules, I have found some that adore it, can't get enough of it, and are great at it. And then I've also found the mules that just will not do it without a huge effort. Some love it, some don't. My dear friend, amazing little rider, not one to pull the bit at all over a jump, leases a mule that is this way. She simply hates jumping, and takes a lot of power to get her over. So it could go both ways. You COULD be easily successful, though, if you get a good one :)
Best of luck!! I loved showing the Mules!! SO much fun! They are wonderful little equines!