Does the page number matter?
tl;dr-  Page numbers are a hold-over from when journals used to be magazines.  The exact number chosen probably doesn't have much practical significance, but it may relate to when an article was ready for publication (camera-ready date) or however the editor might choose to lay out the issue (e.g., with related articles closer to each other).

Once-upon-a-time, scientific journals were basically magazines that collected articles interesting to a specific scholarly community.  Today, libraries still retain some in reference sections and I think that some publishers still actually print them out, but they're mostly funny novelties or historical artifacts.
Anyway, these old-fashion journal volumes would have a table-of-contents that'd refer to page numbers.  Then when the internet came around, they basically stayed the same, except they put copies of articles online, too.  And so, the online copies retain page numbers as a vestigial artifact: they're not really useful to most folks today, but they're still there anyway for historical reasons.
Speculation on what page numbers may've implied
Since page numbers basically reflected order within a printed edition, it'd seem that they likely correlated with how the editors chose to lay out the printed editions.  This may've varied from journal-to-journal.
Possibilities:

Article content.  Articles may've been laid out such that closely related articles would be consecutive.  In such cases, page numbers would correlate with an article's topic.

Camera-ready date.  @user2768 suggested that articles may've been laid out in the order that their content was ready to be amended to the current edition's proof, i.e. the articles' camera-ready date.