Also, ramjets and scramjets don't work at the speeds that commercial airliners fly at, and turbojets are hugely fuel inefficient.

The engines powering commercial airliners are turbofans, similar in construction to a turbojet, but with a large diameter intake fan, that bypasses a lot of cold air past the compression/ignition stage and mixes it with the exhaust air to generate thrust without burning up a ton of fuel a minute.