While I believe an SSD will transform most PCs, the excessive disk usage shown in your post won't likely be solved by replacing the HDD especially after proving the disk is OK with Crystal Disk Mark. High disk usage will cripple any PC and should be corrected before attempting any upgrades, in this situation.
The fact that the disk usage settles down after 6 minutes, clearly illustrates that the activity or problem is related to a program starting with Windows. You may believe that you can't operate without any of the programs currently listed in startup but perhaps understanding which program is causing your problem will better assist you in moving forward.
Performing a clean boot as I suggested earlier will prove your system functions as is and progressively adding additional programs to the startup tab will narrow down the program that is contributing to excessive disk usage.
Before performing a clean boot, I notice in your screenshot of the task manager that OneDrive is enabled in the startup tab, why is this required? I've seen instances where OneDrive will consume excessive resources during startup of Windows.
Also, McAfee is notorious for causing resource problems. If you have a subscription, I'd just uninstall it as a test.
In summary, I would suggest you first focus on reducing the excessive disk usage which will likely resolve the extended start time for the PC. If anything is not clear and can't be resolved with Google Translate, please feel free to ask for clarification.
PS; for an extra $12, I would buy the 240GB SSD. I did same for an old laptop upgrade I did before. I like a bit of additional space on an OS drive so as I have more flexibility to add programs, games etc in the future.
Kingston 240GB