People can only do the best they can do with the resources they have.
If you want to move things off your to do list and get your people to do more, you need to consider this...
You are so busy getting things done, you don’t notice that you have increased your knowledge and moved significantly forward in your thinking.
When you start to hand off things to your people to be done, it's with your current mindset. All that you have learnt along the way to do that specific thing to the best of your ability (Not how you started to perform the task), instead of thinking will this person understand or have the mindset to perform the work so I can set them up for success.
If you are looking at the skills, then that is only half the equation here for them to perform well.
You need to ask what they are interested in and what they want to do in the future to gauge their interest to change their mindset. Just because you have done that because it interest you doesn’t mean they will.
Remember to come back to your outcome and set the person up for success.