There are many advantages of manual testing.
Cost Effective - Manual testing is can save a lot of money in small projects.
Even Automation Can Have Error - Automation is nothing but a manually entered script. Just like an error filled code it can fail. An incorrect automation script can be deduced as a functionality that failed in your application, worst case scenario being an error in the code being passed as a correct functionality. When a code is manually tested, it is ensured that the application is being tested from a user’s point of view with no room for errors.
Testing UI - Automation testing may tell if the UI is working as expected but cannot tell you how well your UI is in accordance to end user preference. This is where manual testing fits in.
There exists no perfect software - Manual testing is necessary to spot functional scripts that could go wrong when automated. Human input is needed in development of test cases.
Manual testing helps in exploratory testing as well. In the new age of automation testing, manual testing is being framed as unnecessary and a waste of manpower. After watching an automation program execute an entire test case library swiftly, trust and faith in automation testing can highly increase. However, the value of manual testing can never be underestimated, and there are some reasons for which manual testing is still prevailing.
Know Why Manual Testing Is Going To Prevail The Industry.
Hope this was helpful.