Of course, the worship of the sun and fire was not something that we normally think of Nordic religion.
Who is your “we”, anyways? History crackpots? 19th Century nationalist scholars?
I do not think most laypeople know anywhere close to enough about Germanic religion that their judgement of whether something fits with what they “normally think of” it holds much weight. Granted, I am a layman myself, but I know enough to be aware that our knowledge of pre-Christian germsnic reöigion is rather fragmentary, as, while runes have existed since the mid-second century BC, they were only used for inscriptions, not literature. The most extensive literature was written by Christian descendants* a few generations after a Christianisation that was preceded by a good while of contact and cultural influence with Christianity, consists of mythology, heroic epics and court poetry (i.e., the religious content may very well be quite different from what your average Norse peasant practiced!), and even beyond all these caveats, what may have be true for the North Germanic peoples of the Viking Age may not necessarily apply to the pre-Migration Central European Germanic peoples (for instance, Odin acquiring the aspect of a warrior deity, diminishing Tyr’s prominence in the process). And what little was written by contemporary sources, on any stage of Germanic paganism, comes from outsiders, Romans or Latin-educated Christian clergy, resulting, among other biases, the Interpretatio Ramana.
* mind you, that does not necessarily mean that it was written with the agenda of demonising their ancestors’ religion - in fact, due to early Scandinavian and Anglo-Saxon kingship being heavily legitimised by divine descend, an euhemeristic interpretation was favoured, with many Anglo-Saxon chroniclers making up genealogies for Woden’s descend from Noah and one Scandinavian writer (I think it might have been good old Snorri, but I’m not sure) claiming that clearly, the Aessir were actually a mighty dynasty from Asia**.
** Wotans Kriecher go REEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!!!!!!!!!!!!!!!!!!!!!!1!
Instead, we think of “eastern” religions like in this account of the Persians.
Of course, the same could be said of the Suavs who worship:
Jasion, Jutrebog, Jarowit/Gerovit likely as the “Moon”
Svarog/Svarozic or Nya as the “fire”
Dadzhbog – Dag-, Dagon – or Łada as the “Sun”
Okay, how detached from everything do you have to be to think that veneration of such primal and fundamentally useful phenomena as the Sun, the Moon and fire are in any way remotely distinctive to any culture by itself?
By the way, this is all based of one sentence in one passage in De Bello Gallico where Caesar, as part of depicting the Germanics as savages, primitive yet untouched by decadence, claims that they seem ignorant of any gods beyond bespoke immediately useful phenomena. He even quotes the entire long paragraph so it is really obvious he is cherry-picking one isolated tidbit that he finds useful for his crackpot theory at face value despite very obviously being an incredibly unreliable point of racist propaganda in a whole slew of text that is very transparently a brutal conquistador aiming for dehumanisation and fearmongering for approval at home rather than factual information.
