Do I need full recovery mode when I have multiple daily backup?
Setting a database to full recovery is not enough by itself to ensure you have point in time recoverability. You also need to take regular log backups. You should also be taking time regularly to test that you personally know how to execute the required commands to actually perform a restore to an arbitrary point-in-time.
In lieu of running loads of home brewed full backups, the fire-and-forget solution you want is probably to just install Ola Hallengren's backup solution. Running this script installs the required objects and deploys the required jobs to manage all of the full recovery databases on an instance. You will find these jobs 1 under SQL Server Agent > Jobs named by default DatabaseBackup - USER_DATABASES ... and similar. Add a schedule to these jobs that suits you 2 and disable other backup jobs to prevent conflicts.
You should still need to regularly take time in the normal course of business to ensure you and others on your team are able to actually restore the backups you have, regardless of how you take them.
1: assuming you're using SSMS here
2: 5 times daily if you like, but probably a bit less is fine
I have created 5 maintenance plans on my SQL server (say 50 !) which generate database backup 5 times daily.
Why not just create one maintenance plan and run it five times.
My exact question: Is generating multiple daily backup with simple recovery model, similar to full recovery backup with longer period?
Full backups or differential backup, no matter in what recovery model you take, are same in terms on what they backup. Now I believe you have combination of full and differential backups and my answer is it all depends on on RPO and RTO (how much data you are willing to loose in case of disaster). A DB in simple recovery model which can afford some data loss and does not needs point in time recovery would just do fine with full and differential backups.
The other important thing is you make sure you restore the backup files on other machine to see that you meet your recovery objective