In fairness, there are some beginners for which such an article is a valid consideration, and it’s often difficult to determine who might be better suited to another distribution.
Some people, perhaps such as yourself, may have a natural aptitude for learning something new. Others don’t seem interested in much more than having everything done for them.
Perhaps the article should actually have been titled “Manjaro isn’t for everyone”, because frankly, that much happens to be true; but, it is what it is. 
Cinnamon with an Arch derivative base such as Manjaro might have performed better than Cinnamon on a Debian/Ubuntu base, which LMDE is.
That said, I may have been swayed by memories of using Cinnamon on a machine of that vintage myself, which I recall performed well enough for my needs at the time.
All hardware is not equal, however.
LXQt really is lightweight and comparable with OpenBox and the like; used with Wayland, it’s sure to be generally performant.
I believe there was a Manjaro LXQt community edition ISO at one time; alas, no more; however, it might be possible to install LXQt from the official repositories manually. Someone else will need to confirm that, and I’m not 100% certain a meta-package exists.
Notwithstanding, OpenBox is likely worth looking at; I’ve seen nothing negative about it’s suitability for low-end (or old) hardware.
I rather like the idea of Cosmic though I confess I know little about it, except that it’s very new and apparently quite lightweight.
Perhaps it will be adopted by Manjaro Summit (an immutable OS) when it’s eventually released, though it’s probably too early to guess.
This Manjaro edition aims to provide an environment more in keeping with new user expectations of an OS; which is something that (like its parent Arch) Manjaro as a rolling release, can’t always provide.
Mod note:- Posts in any language apart from English should normally be made in the appropriate language category. Changing languages mid-thread can be confusing for those who wish to help. Please try to maintain only English responses in general forum areas.
“A while ago a user of this forum suggested that when a long time goes by without updating, I install it again because that would take less problems and less time”
The user was correct in suggesting that. Manjaro, being a rolling release Linux distribution (like Arch) actually requires that updates be managed quite frequently; otherwise, as was often found on maps in the time of Columbus “There be dragons here”.
“I downloaded the latest iso of Manjaro to perform a new installation in case the update fails and to rescue Mabox but the iso also gives me the same error as Mabox. Last night I tried it on my laptop and it works perfectly.”
The problem appears to be kernel support for older hardware.
The current Manjaro ISO’s install a much later kernel (by default) than is optimal for your hardware.
From the Mabox Users Guide;
These kernels are quite old by Linux standards, however, Manjaro does support kernels 5.15 (LTS) and the older 5.4 (LTS), only Mabox uses them by default.
Installing the older kernels might take a little trickery. They will likely need to be installed from a chroot environment, if Manjaro can’t boot as it stands with a more current kernel.
A complication might be that an older kernel is also needed for the USB to boot also. Did Manjaro actually boot from the USB and complete the install, or did it not even get that far?
In any case, it looks that success may possibly take some non-standard workarounds.
“In Mabox they suggested not to make a meld of the pacnew so I stopped making them.”
With Manjaro, attending to .pacnew files is important; sometimes critical, depending upon the changes to be made. These changes are often unique to your system, and there is no reliable way to automate the process at this time.
Mabox might suggest not to touch them, but with Manjaro it is a requirement. On this point, you should probably dedicate some time to understand the reasoning behind the Mabox suggestion and then delve deeper into the reasons to follow Manjaro recommendations concerning .pacnew files.
As previously mentioned, any personally identifiable information is filtered from the inxi output. You can run the command I gave in your terminal and see for yourself.
Without this information provided, any help will be limited mainly to generalisms and guessing.
De nada.