Our ancestors were mostly hunter gatherers and they might have collaborated with the Neanderthal to hunt woolly mammoths for food and material. Then something happened to the latter causing them to become extinct. Suppose in an alternate timeline, could our ancestor species be able to evolve with the ability to fly so that jealousy got the better of the Neanderthal, which would proof disastrous.
To qualify as flying, our ancestors must be able to stay airborne for at least 20 minutes unaided (meaning no tools allowed) and the minimum time for deceleration should be at least 1 minute.