Ever since someone came to repair our sprinkler system, our water sources have been completely jank. If I'm using the water faucet to wash my hands and someone flushes the toilet, the water to the faucet temporarily stops working. If I'm taking a shower and someone uses the water faucet or flushes, the shower stops running water. If we use two or more water sources simultaneously, only drops or a light drizzle of water will run for both parties. Why is this? Is it able to be fixed on our own?
The sprinkler guy most likely had to shut off the water supply somewhere, to facilitate repair.
The first thing you should do is find any/all shut-off valves and ensure they are completely open. While checking them, go ahead and cycle the valve(s) open and closed a few times while observing water flow from an open faucet, this is to ensure the valves still work properly. Gate valves (and other types) are susceptible to failure (what we call a "dropped wedge") where the valve gate/disc/wedge partially or sometimes fully blocks flow, even when opened.
You could also be experiencing an obstruction caused by debris that was jostled loose during the work that was performed. This could cause partial blockage of valves, manifolds, pressure regulator(s), fixtures, etc.