JR Pass or not?

Hi ,
I am totally overwhelmed trying to work out the trains, JR pass and other passes available. I am traveling from Australia to Haneda Airport Japan arriving on the28th October 2023. I like to get to places in the quickest way possible so I avoid wasting time however, if I had the JR Pass and it showed significant savings I would take a slightly slower train. I'm also happy to wear a small loss if the pass is really convenient and saves me a lot of hassle. Below is my itinerary. I'm hoping someone can tell me the best way to utilise the trains. Thanks in advance for your advice.

28 5.25am Tokyo
29 Tokyo
30 Train to Nagoya Change to Limited express to Gero
1 Takayama
2 Takayama
3 Takayama/Shirakawa-Go/ Kanazawa
4 Kanawaza
5 Kanawaza
6 Kyoto
7 Kyoto
8 Kyoto to "Nara" and return
9 Kyoto "Osaka" and return
10 Kyoto "Universal Studios" and return
11 Kyoto
12 Train to "Himeji hop off then later continue to Hiroshima
Book 9am Shinkasen.44 mins to Himeji, then 56mins to Hiroshima
Allow 30mins walk to castle, an hour and a half at the castle and 30mins to walk back in Himelji
Catch a 1.00pm train to Hiroshima. Arrive 2pm.
13 Hiroshima Hiroshima
14 Tokyo "Catch bullet train to Tokyo
15 Tokyo
16 Tokyo to Nikko and return
17 Tokyo
18 Tokyo DisneylandSea
19 Tokyo Kamakura and return
20 Tokyo Leaves 10pm Haneda Airport

First off, if you get a pass, you'd better get the exchange order before the prices are jacked up about 70% in October... otherwise, it pretty much doesn't matter how much you ride, you'd never justify one.
Second, you'd need a 21-day pass for your plans - if you cut it down by a day, you could get a 14-day pass.
You could for example cut the day trip to Osaka and see it in the evening after a day of sightseeing in Kyoto (the city is much better in the evening anyway).
But if you want the 21-day pass, I ran the numbers, and if you take JR to Nikko, you can make it pay off. Not necessarily the "best" way to do it all though. Tokyo to Gero will take you about 4 hours. Plus, if you are unaware of it, there is no rail access to Shirakawago - you'll need to pay for the buses between there and Takayama/Kanazawa. For Himeji, the castle is excellent, but don't skip the Kokoen Garden next to it as well.
https://goo.gl/65ZtRi

For Nara, you could if you want spend half your day seeing Uji along the way (Byodoin, Mimurotoji temples) and the rest in Nara Park (deer, Todaiji, Kasuga Shrine, Isuien & Yoshikien Gardens, etc). For Hiroshima, you have about 1½ days which is doable - you can see the Peace Park and hopefully another place like the Shukkeien Garden there as well. You didn't specify if you are also seeing Miyajima.

if I had the JR Pass and it showed significant savings I would take a slightly slower train. I'm also happy to wear a small loss if the pass is really convenient and saves me a lot of hassle.
Based on your route, you will not save much, and IMO the passes, especially over the last year, add hassles rather than removing them. The additional transfers, fewer trains, slightly slower - it adds up.

The first part of your route is basically Tokyo to Kyoto via Takayama and Kanazawa. Cheaper is to go via Matsumoto, but many people go via Nagoya. That would fit into a 7-day period, but a pass just for that wouldn't pay off. The reason for mentioning the 7-day bit is because you have a big pause in Kyoto where the national pass will be of limited value and just burn days.
You then have a piece at the end Kyoto to Hiroshima to Tokyo. Again, that would be less than the 7-day pass cost.
Your long-distance travel is across 15 days, so the 14-day pass does not cover your travel. Even dropping a Kyoto day to make it fit into 14 days, you will not save much.

Thank you both so much. I'll have a good think about what I do. I might see if I can tweak the itinerary as suggested to make use of a 14-day pass or just buy individual tickets. I think I can buy the pass before we leave in late Sept. Appreciate the advice.

Sorry, just one more clarification.
If I travel without a JR Pass to Gerp and take the Nozomi Shinkansen from Tokyo Station. The train will take me to Nagoya, Should I transfer onto the JR Tokaido Line New Rapid Train going to Ogaki and change at Gifu Station and transfer to your last train to Gero, the Limited Express Hida OR transfer at Nagoya onto the Limited Express Hida to Gero. I believe the second option takes about 30 mins longer but may be a prettier or more scenic?? way to travel. Any opinions?

Ken, I am hoping to do Miyajima Island.

Again thanks for your detailed answers.

Day 1, 2 : Tokyo
u can board Hydrogen fuel cell bus from Toyo cho- Tokyo Teleport .It is Lifetime experience

I recommend getting a 7 days JR pass for kyoto to Nara , to Hiroshima, and back to Tokyo. As the travel from Tokyo to the nearby places of central Japan alps is not so costly to warrant purchasing the 14 day pass