MYSQL 5.6 upgrade fails on conflicts:
file /usr/share/mysql/charsets/README from install of mysql-community-common-5.6.47-2.el6.x86_64 conflicts with file from package mysql55-server-5.5.62-1.23.amzn1.x86_64
First thing is the End of Life (EOL) for MySQL 5.6 is in February 2021 so please plan to upgrade.
Second, there are a lot of things that can cause upgrading issues which is why there is an 5.7 to 8.0 upgrade utility in the MySQL Shell (mysqlsh) but sadly you are not making that upgrade.
Please follow the guide for the MySQL YUM at https://dev.mysql.com/doc/mysql-yum-repo-quick-guide/en/