They are:
Cosmic rays
Source of an element that never existed
Quoting wikipedia:
Cosmic rays are also responsible for the continuous production of a number of unstable isotopes in the Earth's atmosphere, such as carbon-14
Perhaps with thermal tangles
Quoting a part of the wikipedia article (with a message about possible neutrality issues):
A role of cosmic rays directly or via solar-induced modulations in climate change was suggested by Edward P. Ney in 1959 and by Robert E. Dickinson in 1975. The idea has been revived in recent years, most notably by Henrik Svensmark, who has argued that because solar variation modulates the cosmic ray flux on Earth, they would consequently affect the rate of cloud formation and hence the climate. However, other scientists have vigorously criticized Svensmark for sloppy and inconsistent work
So, it is something actually being debated and at least unclear. However, the riddle verse contains the word "perhaps", so it is not taking it for granted nor as refuted.
Some of us are not as neat
Quoting from wikipedia:
Cosmic rays attract great interest practically, due to the damage they inflict on microelectronics and life outside the protection of an atmosphere and magnetic field
Our name is a misnomer
Quoting from wikipedia:
The term ray is a historical accident, as cosmic rays were at first, and wrongly, thought to be mostly electromagnetic radiation.
An electronic errand?
Quoting from wikipedia:
Of primary cosmic rays, which originate outside of Earth's atmosphere, about 99% are the nuclei (stripped of their electron shells) of well-known atoms, and about 1% are solitary electrons (similar to beta particles).
Also, the answer to the "Some of us are not as neat" part also might apply.
Hard to pinpoint
They were first detected only at the first years of the 20th century, even if many of them might be hitting you at this exact moment. They could be correctly identified only in the 1930's. See the "Identification" section on the wikipedia's article for details. They require quite softiscate equipment and technology in order to be detected and identified.
Following death
Quoting wikipedia:
Early speculation on the sources of cosmic rays included a 1934 proposal by Baade and Zwicky suggesting cosmic rays originated from supernovae. A 1948 proposal by Horace W. Babcock suggested that magnetic variable stars could be a source of cosmic rays. Subsequently in 1951, Y. Sekido et al. identified the Crab Nebula as a source of cosmic rays. Since then, a wide variety of potential sources for cosmic rays began to surface, including supernovae, active galactic nuclei, quasars, and gamma-ray bursts.
Supernovae are massive stars that blow up spectacular deaths. Nebulae (like Crab Nebulae) are supernova remnants, so created by some star deaths. Gamma-ray bursts are theorized to be created in supernovas and neutron stars merges (neutron stars are a possible result of supernovas). Active galactic nuclei and quasars are brilliant accretion discs of supermassive blackholes, and both a black hole and their accretion discs are implied to death of stars.
We fade too
When cosmic rays interact with Earth's particles (mainly in atmosphere), they'll fade. It is easier to explain with this wikipedia's picture:
And quoting the text:
Primary cosmic rays primarily originate from outside the Solar System and sometimes even the Milky Way. When they interact with Earth's atmosphere, they are converted to secondary particles.
When cosmic rays enter the Earth's atmosphere they collide with atoms and molecules, mainly oxygen and nitrogen. The interaction produces a cascade of lighter particles, a so-called air shower secondary radiation that rains down, including x-rays, muons, protons, alpha particles, pions, electrons, and neutrons.