AWT used native widgets. It looked less alien than Swing.
Swing also had a theme engine (PLAF I believe it was called) that wasn't terrible. It could look like Motif or Windows or Apple had one that looked like Aqua, set as their default back when they bundled JVM. https://en.wikipedia.org/wiki/Pluggable_look_and_feel
Originally, that platform L&F was pretty bad - for example, fonts were rendered using some bundled engine (FreeType?), instead of the OS text APIs. On Windows, at least, this meant no ClearType, which made all Java apps on XP+ with default settings stick out like a sore thumb.
Swing also had a theme engine (PLAF I believe it was called) that wasn't terrible. It could look like Motif or Windows or Apple had one that looked like Aqua, set as their default back when they bundled JVM. https://en.wikipedia.org/wiki/Pluggable_look_and_feel