There are 20773 common words, and given jisho's database is JMDict, I guess they're all from a certain book that complied 20000 words or so for Japanese beginners, I forgot its name.
Sure it's good to know all common words, but there's a good number of them that have to do with politics, etc. so depending on what you read or what you're learning Japanese for you might not come across them as often as you'd expect for a "common" word.
As a conclusion, my tip is to learn words as you see them, taking the common word marking as a word list is not very productive.
If your objective is to be near-native you should learn a lot more than common words. Just because a word isn't marked as "common" doesn't mean you won't see it. Not only is the data not always accurate, but depending on what you do in your life you might need specific uncommon words a lot more than some of the "common" ones.
The definition for what is considered a common word in Jisho is the explanation here for what is marked as (P) under the nfxx heading: http://www.edrdg.org/wiki/index.php/JMdict-EDICT_Dictionary_Project#Word_Priority_Marking
I have some ideas for ways to improve the common marking to be more considerate of context such as written and spoken language.
How does jisho.com decide whether a word is a "common word" or not?
Are the common words really that common? Should someone who's goal is to eventually have near-native level Japanese try to learn all common words he comes across?