You seem to be correct, and I am wrong.
After spending at least 2 minutes of research, it seems that Jomon and Jimmu are not at all related to each other (at least not what my simple research reveals, which is nothing at all).
Jomon is a specific tribe or group of ancient people, am I correct?
Jimmu or Jimnu Tennou is the first Emperor of Japan, and it was "the onyomi (Sino-Japanese reading) of 神武天皇. According to various articles, Wakamikenu no Mikoto was his actual given name". (your quote).
But as for the quotation reference to James, or Jaemes, that comes from the 1912 book,
The Lost Language of Symbolism by Harold Bayley, and I am not so sure I would discount his reasoning of its origins being
Jaemes, much like the French name
Gemmes that you cite.
Jaemes or Gemmes, and yes, I did find a winding, twisting path from Ya'akov to James...
"The name Ya'acov became Iakobos in Greek. If you keep in mind that in some languages the sounds of b and v are quite similar (in modern Spanish they're identical), the Hebrew and Greek versions of the name look quite similar. By the time the Greek Iakobos became Latin, it had turned into Iacobus and then Iacomus. The big change came as some Latin morphed into French, where Iacomus was shortened to Gemmes. The English James is derived from that French version."
Many Spanish names sound similar to their English counterparts, but Diego in English is James, which sounds much different than you'd expect.
www.thoughtco.com
Miwasatoshi, I don't think you are wrong in your opinion, but I don't think Harold Bayley's 1912 opinion is also wrong... I think you both could be right.
Jaemes and Gemmes are too close to call.
PS...I didn't make the claim, only passed on the opinion. Thanks anyways for the clarification.
My basic question though...
who was Mutshuito speaking about, what tribe was he talking about that was 10,000 years old, when in 1868, "...the late Emperor of Japan, thus addressed his people:--"My house, that from Jimmu Tenshi, has ruled over Japan according to the will of the Gods, is the oldest dynasty on earth, and is carried back 10 thousand years beyond Jimmu to the time when our Divine ancestors laid the foundation of the earth."