What meaning is the conjunction "or" (aw) intended to give in this verse, comparing this example with the previous one (v. 17)?

Imām Ibn al-Jawzī (d. 597 AH / 1201 CE) summarized the scholars' opinions in his book "Zād al-Masīr" as follows:

1. Choice: the reader is given the choice between using the first example or the second example for them.
2. Ambiguity: It is used to leave it ambiguous although Allah knows the truth of the matter. It is as if He said, "Their example is like one of these two," similar to the verse "For they are like stones or harder" [Al-Baqarah: 74] It is common for the Arabs to leave things ambiguous where precision is not needed.
3. It means "rather": It is used in the sense of "rather" or "actually". (As if to say, "Their example is like this... in fact, it is like this.")
4. Categories: It is used to differentiate, meaning that some of them resemble the one who kindled a fire, and some of them resemble the parable of the people of the raincloud. This is similar to the verse: "They said: be Jews or Christians" [Al-Baqarah: 135]. Meaning: one group - namely, the Jews - says, "Be Jews," while the other - the Christians - says "Be Christians."
5. It means "and": This is similar to the verse: "whether you eat from your houses or the houses of your fathers" [An-Nur: 61]. In this case, "or" functions similarly to "and".
6. Expressing doubt on the part of the addressees: According to this interpretation, "or" is an expression of doubt, but on the part of the addressees, not Allah, who is above any doubt. This is similar to the verse: "while it is easier for Him" [Ar-Rum: 37], meaning, the resurrection is easier than the first creation according to what you perceive (not that one is actually easier or harder for Allah).