This is a fun exercise and is going to contain assumptions:
Embery, Joan with Ed Lucaire. Collection of Amazing Animal Facts. 1983.”Scientists estimate that there are one quadrillion (1,000,000,000,000,000) ants living on the earth at any given time.”one quadrillion ants. More recent estimate point out to about 10 times more. 10,000 Trillion is the number and each of them weigh 4×10^(-3), so average total weight of all ants is 4×10^13 grams
The average Human is about say 65 Kgs(6 5000gms) and we are about close to 7 billion people (7×10^9)*6.5×10^4) = averages to 4×10^14.
So empirically we outweigh ants ten times to one. but there is no way of saying how many ants are there and what is the average of people. I could argue that at a point of time we would have weighed less, equal and then exploded to outweighing them.