>The big difference is the impact speed, so bird strike damage of a 4 lb bird impacting with 300 kts is quite different to an 150 lb person impacting with 10 kts (or something like this if you have just left the plane some 20 ft in front of the engine), because impact energy is 24 times higher ! <
Sorry to disagree with you volume but your analogy above is not correct.
In either the 300 kt case or the 10 kt case the bird or body does not impact the engine blading with flight motion energy.
It presents itself between the individual blades and the blades do the impacting with their fixed rotational velocity The effect of ingested speed iis only to increase the size of the individually ingested slice bits.
I have an idea that some folks have seen the pictures up close of UA811 engine .I can also tell you that by virtue of the damage to the inlet cowl lip that the ingested speed from the stuff going in was much higher than 10 kts.