The two ideas from the excerpt which would be most appropriate to include in a summary are the following ones:
1- “Art is the foundation of what it means to be a human.”
2- “But it is everything else that will suffer when we lack art and beauty in our lives.”
Both sentences are appropriate for a summary, since they comprise complex, intricate themes with the use of only a few words. These themes refer to the most relevant ideas from the text, the central ones.
In sentence number one there is the philosophical tone, and yet it is a short sentence.
In sentence number two, "everything else" is mentioned, which is a broad concept.
Both the human condition and the things besides it will certainly be found in the original text in a developed way.