Will low compression on all 4 cylinders of a 2.0 engine prevent it from starting?

Yes, low compression across all four cylinders will almost certainly prevent a gasoline 2.0L engine from starting, or at least from running properly. The compression stroke is crucial for igniting the air/fuel mixture. Insufficient compression means the mixture won't be compressed enough to ignite reliably, resulting in a weak or absent spark. The engine might crank, but it won't fire consistently, if at all.