Agree with the above. First, get a bike fit. Then just ride your bike. My recipe is to ride away from home until you're tired. Then ride back. Endurance doesn't start until you start to endure. Everyone used to be an endurance human. Fiber type doesn't matter at all. You put the deer on your shoulders and walk the 10 miles home. TdF sprinters first have to be near the front of the pack after 200k to even get a chance to sprint. And ride hills. "See hill, ride up it." I used to ride with a group where if I could see a hill in the distance, I knew we'd be riding up it. That really helped in the long run though it hurt in the short run.
All that said, bike fit first. And maybe a decent road bike to go with that bike fit. Go shopping.
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