Is possible to define a bash script to run interactively by default?

Sourcing your .bashrc is not a good idea. You could create a .bash_alias file with your alias and then source that file in your script and use shopt

something like:

shopt -s expand_aliases
source ~/.bash_alias

Bash man page states:

Aliases are not expanded when the shell is not interactive, unless the expand_aliases shell option is set using shopt (see the descrip‐ tion of shopt under SHELL BUILTIN COMMANDS below).

If you add the -i option to your hashbang(s) it will specify that the script runs in interactive mode.

#!/bin/bash -i

Alternatively you could call the scripts with that option:

bash -i /path/to/script.sh