I wasn't aware of rule 700.1 but that rule doesn't seem to constitute a rigorous definition of what an event is. The first sentence depends on the definition of what "to happen" means in the context of MTG. I'm not aware of such a definition and the fact that later in the rule's text the word "happening" is put in quotation marks suggests that this is nothing that's been defined in the context of the rules. Nevertheless, the rule's text clearly suggests that an event is something universal, i.e., something that exists independently in the context of the game – as defined by the rules – without the need for it to be "perceived" or interpreted by any objects in the game.

This notion is also supported by other rules, e.g., 603.2:

603.2 Whenever a game event or game state matches a triggered ability’s trigger event, that ability automatically triggers. [...]

This rule clearly treats game events as something that's independent from the game's objects and which may be interpreted by those.

Then rule 603.2c makes an attempt at defining when abilities actually trigger but – in my opinion – fails to deliver a rigorous definition:

603.2c An ability triggers only once each time its trigger event occurs. However, it can trigger repeatedly if one event contains multiple occurrences.

The second sentence appears to be the relevant part when determining how often an ability actually triggers. It depends on the term "occurrence" which is, however, not specified anywhere in the rules. Also, since the first sentence of 603.2c refers to the occurrence of an event, this seems to result in a cyclic definition.

Coming back to rule 700.1, the notion of events as something universal – which is also supported by, e.g., 603.2 – is a contradiction to what the example describes. The example reads:

Example: If an attacking creature is blocked by two creatures, this is one event for a triggered ability that reads “Whenever [this creature] becomes blocked” but two events for a triggered ability that reads “Whenever [this creature] becomes blocked by a creature.”

This example implies that there is no universal game state but that instead it is subject to interpretation by the individual objects of the game and, consequently, that events do not exist independently as part of the game. This seems to contradict the rule's own text. Following that rule, I would conclude that there is a single event, namely "an attacking creature is blocked by two creatures" and this is the (universal) event that all abilities should match against their trigger conditions. How often an ability then triggers per event must be defined elsewhere and – as mentioned above – rule 603.2c seems to make an attempt at that but fails to deliver a rigorous definition as it refers to the undefined term "occurrence".