Can you identify if this is worth it? Transend vs SSD on old Mac Quandry??

For my Macbook Pro 2015 - ancient i5 2.9 8gb.

I have this :

Transcend 2TB Thunderbolt USB 3.0 External Hard Drive for MAC (TS2TSJM300)
5400rpm

124mb and 125mb read / write

I need a fast SSD - HOWEVER all the new SSDs all come with USB C or Thunderbolt 3. Which means when connecting I will not feel the speed benefit per pound spend because I will have to connect to either USB 2 or Thunderbolt 2.

So I found this.

Transcend JetDrive 855 480GB Thunderbolt NVMe Pcle SSD Upgrade Kit for Mac

Compatible with MacBook Air 11" & 13" (Mid 2013 - 2017), MacBook Pro Retina 13" & 15" (Late 2013 - Mid 2015), Mac mini (Late 2014), and Mac Pro (Late 2013)
Up to 1,600 MB/s read; 1,400 MB/s write

Do you think for the £229 it will be a worthwhile purchase???

www.amazon.co.uk/Transcend-JetDrive-960G...la-549945046028&th=1

Or is it still better to go for a newere faster USB / Thunderbolt 3 SSD and down grade the connection to work on my mac?

I have a rMBP 2015 and it is USB 3.0.
support.apple.com/kb/SP719?locale=en_US

Connecting to T'bolt will help give you more speed, regardless of the version.

5200rpm drives are unacceptable (too slow) for video editing. You'd get faster results with a dual drive, 7200rpm RAID 0. I have one that is USB 3.0 at the TV station where I work, and it is WAY faster than the single SSD T'bolt drive I have connected. So SSD by itself doesn't mean all your troubles are solved. A dual 7200rpm drive RAID 0 unit would probably be cheaper than an SSD, faster, and you'd get more storage capacity.

The unit yo link to, IMHO is a total rip off. You're getting next to now serious drive capacity. I'd suggest looking here.
eshop.macsales.com/item/OWC/MED3ER7T02.0/

Thanks -

Yes it more a question of

Is it even worth bothering with an SSD if I can only connect it to to my older Mac - i.e. Thuderbolt.
I already use Thunderbolt 2 with my slow drive.

So in other words - its is worth getting any SSD if I have to down grade its performance due to my available sockets.

I guess I should have said that in the first place! My mistake.