Except for the use of stylized hieroglyphs ~ that is, the cuneiform wedge orthography ~ Egyptian and Sumerian aren't particularly distinguishable. Arguments are currently being advanced that the Sumerian system was transmitted to Egypt as it was being developed in Sumer, and further that the earliest Chinese hieroglyphs were substantially influenced by the writing at Sumer ~ and probably developed by trained scribes from Sumer.
Some of the deer stones in Mongolia are about 7,200 years old and bear characters that appear to be meaningful ~ some of which show up in other later writing systems. The deerstone code hasn't been broken yet.
Contemporaneous with the earliest deerstones there are pictographs in the Kola peninsula (the Sapma, home of the Laplanders or Sa'ami, the ancient indigenous population of the far North) that may be interpreted even today.
Philologists argue that the Sa'ami languages of today have the same root as ancient Sumerian, and that there is some link, not yet figured out, between the pictographs and the cuneiform wedge hieroglyphs.
Sumerian was an isolate as far as can be determined now (since it was uniquely a literate society), and has no living relatives. I’ve never seen any philologist argue otherwise. It was agglutinative, but its morphemes were not carried on anywhere else; Turkish, Korean, and Japanese are sometimes grouped together (particularly Turkish and Korean), and all are agglutinative, but other agglutinative languages aren’t related to any others, or are in small families that are unrelated to other agglutinative families.
Here’s one Finno-Ugric chart:
http://www.helsinki.fi/~tasalmin/fu.html