The 20-year-old smashed two fours and half a dozen maximums in a brutal 29-ball knock that helped the tourists chase 178 with five deliveries to spare.
Scotland looked to be in control after ending a 60-run opening stand between Regis Chakabva and Craig Ervine and then reducing Zimbabwe to 63 for three in the 10th over.
But Wessley Madhevere, with 43, and Shumba added 99 in nine overs to take Zimbabwe close before the latter and Ryan Burl finished the job.
George Munsey struck 54 off 30 deliveries, passing 1,000 T20 international runs in the process, as Scotland racked up 177 for four after winning the toss.
Richie Berrington hit 44 while Calum MacLeod, with 39 off 29 balls, and Michael Leask, who made 17 off five deliveries, took 30 off the final over to inject late impetus.