Hello Slip and Turn!
May I postulate a speculation? You raise a good point that perhaps MCAS might be a bit of a red herring, that perhaps all was not right even before rotation. The behavior of the flights that crashed did not seem 'normal' very soon after takeoff. It has occurred to me that the 737 Max and its immediate predecessor are not the same airframe: is it possible that the 'microenvironment' (aerodynamically speaking) around and near the AOA sensors could be significantly different at similar points in the flight envelope. The giant engines and their nacelles (placed forward of it's predecessors) might possibly result in erroneous interpretations of AOA and airspeed secondary to different airflow patterns vs those of the immediate predecessor to the 737 Max. This microenvironment of airflow might not have been explicitly modelled or tested in the test regime. Just my two cents. Part of my work knowledge (in Anesthesiology and Critical Care) centers around constant troubleshooting of what our biomedical sensors are telling us: is it accurate data or is it compromised somehow by the microenvironment, kinks in pressure tubing, etc. Just a lowly PPL myself, but I always envision the takeoff roll and the time around and after rotation as a very dynamic situation. Putting a new, giant and powerful engine (in a different place) on a 50 year old frame might induce novel anomalies to the sensors.