The phrase "to skim the surface" means to only get a basic or superficial understanding of something without delving deep into its details or complexities. Full definition
Instead of skimming the surface of their destination, the slow traveler immerses. (young-germany.de)
We've only just skimmed the surface of what's in this show. (timeout.com)
The AKC standard describes them as «friendly, fearless, alert, and obedient» and this sounds like a simple combination of traits, but it actually only skims the surface of what the breed should be. (justweimaraners.com)