If the question is limited to "entry-level road bike" (I assume you mean "drop bar sport bike" to be used on road), there's not so much choice: alumiminum. It's the only material you'll find on entry level bikes from reputable brands.
Carbon is considered to be a performance material, so you will only find it on mid-range bikes and up. In term of durability, carbon is also probably the material where you have the most custom parts, so on the long run, it might be difficult to find some parts (seat posts, stems, forks,...)
Steel on road bikes is a niche, quality steel bikes are at the same price as carbon bikes (typically on long distance touring and some gravel bikes). You can easily find steel on department store bikes, that should be avoided at all cost. You can also find quality steel city bikes.
About your comment on repairability: you didn't indicate the use of the bike, but I would say that repairability of the frame is dominantly a concern for long distance touring bikes (that are used with heavy loads on bad roads).
About the fatigue: the fatigue on aluminium is a "characteristic" that is known in the industry. Frames are designed against some standards, that specify the number of cycles the frame has to endure before failing. The lifespan of the frame then linked to "your use vs the standard" (and maintenance, care, conditions you are riding, your weight, the load,...).