It's possible, but like what everyone is saying it will be tight. I would take Uber or Lyft over the Magic Express so you have more control over the transportation situation.
For reference, last year (pre-covid): we landed at MCO at 6:00am from our red eye flight, we got on the ME; Before arriving to CSR, we stopped at Pop and AoA; we were able to check our bags in at CSR, change clothes, eat at El mercado, take the bus, and arrive to Magic Kingdom by 9:30am.