What are the main routes by which Humanitarian aid arrives to Gaza? Who is taking care of transportation (gouvernements, non-government organizations, private contractors)? What proportion of the aid is channeled via each route?
As the situation on the ground is changing, so will answers to this Q. So it's somewhat futile to try to answer it definitively. E.g. someone might have included the US floating pier (JLOTS) in an answer, but news is that it broke up in heavy seas yesterday. (N.B. they plan to tow it to Ashdod and repair there, then bring it back.)
There was aid through the Rafah crossing until there wasn't (about a 3 weeks ago) and also there wasn't back early in Oct. There wasn't aid through the Kerem Shalom in the earlier part of the war, but then there was since December. There weren't any air drops earlier in the war, but then there were some. Likewise the opening of Ashdod port for aid and Erez crossing is relatively new thing apparently since April. Etc., etc. OCHA has been much lagging in updating their database with summary data and following all their "flash updates" is too much work for average person to come up with some kind of summary as to how much entered from where and when. The same applies to COGAT tweets. N.B. there are two Erez crossings opened "East" and "West"--the latter since mid May. I'm not sure how far apart they are. Ah, yeah, OCHA managed to give us a map May 27 one below, that also shows the more obscure "Gate 96".
OCHA (a UN organisation) also has this breakdown by entry point (in the same brochure).
The OCHA breakdown provided a few days earlier is perhaps slightly more insightful as to recent (May) developments as it put a breakpoint at May 7 when the Rafah offensive seems to have started. (I'm not sure what's special about May 24/23 when the latest OCHA update has a breakpoint.)
I'm not sure how much COGAT (the Israeli government) agrees with that, because sometimes they disagree. There's also a caveat attached to the OCHA brochures themselves:
Commercial trucks are not captured in the above totals following 7 May. After 7 May, the UN was unable to directly observe the arrival of private sector cargo at Kerem Shalom crossing due to insecurity. Fuel is not included.
Also, the older OCHA updates form May 20 and before don't seem to have a breakdown by entry point, so my recollection that OCHA didn't use to provide that info is apparently not that wrong. Their May 20 report didn't include Erez data at all, resulting in substantially lower counts for May. (This is disclosed in the fine print of that older report, that they only included Rafah and Kerem Shalom then.)
COGAT also puts out some similar brochures, but TBH, I'm not too sure what they mean by "The Jordanian route" for instance. (Presumably stuff that came via the Allenby bridge). Latest breakdown (of sorts) I found was from May 15 though.
The main COGAT webpage has more up-to-date data (up to May 24 as I'm writing this), but it's not broken down by some kind of 'route', except for JLOTS and air drops. The rest is all (implicitly) land route there, right now.
(It's also not too hard to spot the ongoing/aforementioned disagreements with the UN, e.g. COGAT claims 298 trucks entered on May 24, while OCHA reported 160 [total, not average] for May 24-26.)
FWTW, as your Q seems to be about how Israel/COGAT defines or manages those 'routes'. The best I can do is give you this flowchart they provided:
Thus far I've not found more textual explanation that goes with it.
The route that 'goes to' (or passes through) Jordan is probably used by those countries that are closer to it (besides Jordan itself.) E.g. there are reports that Iraq and Turkey delivered some aid that way. Some World Food Programme convoys also entered from Jordan (first one in December apparently), but others passed through Egypt (as early as October). And yet others from the sea directly through Ashdod, more recently (April).
As for Egypt (that you seem also wonder about "a land route via Egypt - it is not clear where it goes to"), it was the main hub/route of aid until recently (Rafah offensive start), according to COGAT (infographic above). That surely included UN-umbrella aid, Saudi and UAE too--they shipped by cargo plane to Egypt--, but also Turkey sent aid that way sometimes.
Whether that 'route' still 'goes to' anywhere since the Rafah offensive, who knows what the future holds? The COGAT report from May 15 says 0 trucks came that way May 9-15 (in that infographic above), but more recent news reports say that an agreement was brokered by the US to ship all that through Kerem Shalom for now. So maybe Egypt still has a role to play as a hub for routing some aid.
