I had doubts that it would help. For a 2015 model, if it was a driver in the kernel, it would have most likely been supported by 5.8 or 5.10.
Although we know you have already tried some of the tips here:
https://www.maketecheasier.com/fix-touchpad-not-working-linux/
You might read through in case there are some things you have not yet tried.
You may also try testing LiveUSB of other distros and see if any of them have support for your notebook touchpad. It's worth checking.
I found that this issue does happen in some of the hardware. And if it does, it carries itself to all distros.
In the attached thread some people have found the solution, but I cannot understand half of what is written 
We can ignore the bit about the kernel, since you have already been on the 5.13.
It suggests ading a Grub parameter:
sudo nano /etc/default/grub
Arrow key down to this line:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" and change it to look exactly like this:
GRUB_CMDLINE_LINUX="i8042.notimeout i8042.nomux"
Once done, hit ctrl+x to exit, then the y key to say Yes to save, then the enter key to save the configuration and exit.
Now, update grub (essential step):
sudo update-grub
Reboot and test - run the command to see if your device is even detected.
cat /proc/bus/input/devices
Or xinput list
Thanks for all your support @Aravisian. Seems like I have to try some other distro as Zorin is not ready to detect my trackpad 
Except if @Aravisian you can guide on this specific solution mentioned in the thread. I hope this will be last time I will be bugging you
Did you try Aravisian's this answer?
Yes, completely.
And it didn't work?
Aravisian summarised the solution of the thread that you referred to in your above posts.
Yes. But I just checked that this solution also did not work for the guy who posted this. Then he mentioned another solution involving hid_i2c. I am not sure how to execute it.
I can't help you with that but in case you decide to switch distros...Go for Pop! OS otherwise for a Debian based distro that is not Ubuntu based.
In all honesty, as I have paid for Zorin, I will prefer getting this solved (though the official support is pretty slow). Also, with the modern web, OS now has a very limited role compared to browsers. If I have to make a switch, I will definitely first try the Lite Pro and then will see where to move forward. But I won't be needing a switch is this issue get's solved.
You are already using 5.13.0-27 if you are fully updated on Zorin OS - I do not know if you are ready to compile and build a kernel from source.
You may try the module probers in any case:
modprobe i2c_hid
modprobe i2c_hid_acpi
The other suggestion is
sudo nano /etc/modprobe.d/blacklist.conf
Paste this line at the bottom of the file by using the arrow keys to get to the bottom and creating a new line with enter key
blacklist elan_i2c
Then tap ctrl+x to exit, the y key to say yes to save, then the enter key to save and exit.
Touch-pad is not my specialty, but there's a PPA with the latest kernel - if everything else fail you could try this.
I see that TuxInvader maintains his awesomeness...
These solutions feel too tricky for me. Anyways, I installed Zorin Lite Pro but the issue is still there. And now I discovered a new dimension to this problem: my trackpad is detected (on both Core and Lite) but as a PS/2 Generic Mouse. Thus it is only doing functions of a PS/2 mouse 
This is a hint, at least. Searching that issue mostly just gave the same solutions we have tried here.
This one offers something new:
But it is outdated.
Yes the PPA has been removed.
I also found that in general, updating the kernel solves this issue
I tried and installed 5.16. I tried bothwget https://raw.githubusercontent.com/pimlie/ubuntu-mainline-kernel.sh/master/ubuntu-mainline-kernel.sh
and the TuxInvader PPA. It gets downloaded, in fact got installed through software update, but the kernel still shows 5.13 (though it should be 5.16). It does not even shows in advance option during boot (though it does show 5.11 and 5.8 that we previously installed.)
Seems I have made my Zorin installation too buggy. Will give it a fresh install once the kernel updates (and if it solves the issue).
So this guy made the most comprehensive task list for this issue
