Come on Alex.
Rainbows are not circular. There is another phenomena called a halo that may be what you are refering to. Rainbows are caused by water droplets hanging in the air acting as prisms reflecting sunlight to an observer. Please provide us a reference to the completely circular rainbow. A picture or description or website? I'd love to see it or read about it.
7 notes in the musical scale? Which musical scale are you referring to? There are 12 notes (per octave) in the "equal tempered" scale which is the compromise that folks came up with so they could make a piano that'd play in more than a couple of keys. It's based on the 12th root of 2.
Seven notes of a diatonic scale is the sound palate most folks work from but if you start and stop from a different place then you have a different relationship between the notes. These are "modes" like Ionian (1), Dorian (2), Phyrigian (3), Mixolidian (5), Aeolean (6).
In the west there has also been Pythagorean, Just Diatonic and Chromatic tunings of scales which have different frequency relationships between the notes. There are other non-western Arabic scales, Hindu scale (22 notes), pentatonic scales (5) and use different tonal centers.
The reference or basis for all tuning has risen from A = 432 Hz to A = 440 Hz to some folks even playing A= 442Hz. So where is the ground of being? How do we chunk it?
Light. Are there only seven colors? Or is there an infinite number of colors? What do you mean by your statement "like notes they repeat at a higher frequency" ?? Light is a frequency specific phenomena interpreted by our nervous systems. Do you know anyone who sees (unaided) into the ultra-violet or infra-red portions of the spectrum?
Seven year replacement for cells? It varies.
Chakras? Gotta take others word on that. I do not see them. Do you?
I suspect the seven number comes up because of the "7 plus or minus two" that most folks can hold in conscious attention rather than a intentional segmenting of the universe.
But I could be wrong.