In the US you often have people who take a job after their undergrad/masters and then come back for a PhD. Undergrads can also help as free labor / paid summer interns, but are unlikely to be first author. Academia is also a rat race, and any kind of publication/student prize/patent/recommendation letters helps to “propel” you into better labs/better citation record/funding. Not having those isn’t the end of the world, and you shouldn’t compare yourself to others and worry about that.