This is the way to go for your objective:
Play an action on a batch of files
The Batch command lets you play an action on a folder of files and subfolders. You can also use the Batch command to populate a template for data-driven graphics with different sets of data.
- Choose Batch from the Actions panel menu.
- For Play, select the action you want to play.
- For Source, choose the folder on which to play the action. Or select Data Sets to play the action on each data set in the current file.
If you select a folder, you can set additional options for playing the action.
- For Destination, specify what you want to do with the processed files. You can leave the files open without saving the changes (None), save and close the file in their current location (Save And Close), or save the files to a different location (Folder).
Depending on the Destination option you select, you can set additional options for saving the files.
- Specify how you want Illustrator to handle errors during the batch process. If you select Log Errors To File, click Save As, and name the error file.
- Click OK. Saving files using the Batch command options always saves the files in the same format as the original files. To create a batch process that saves files in a new format, record the Save As or Save A Copy command, followed by the Close command, as part of your original action. Then choose None for the Destination when setting up the batch process.To batch-process using multiple actions, create a new action, and record the Batch command for each action you want to use. This technique also lets you process multiple folders in a single batch. To batch-process multiple folders, create aliases within a folder to the other folders you want to process.
If you select Folder for Source, you can set the following options:
- Override Action “Open” Commands
- Opens the files from the specified folder and ignores any Open commands recorded as part of the original action.
- Include All Subdirectories
- Processes all files and folders within the specified folder.
If the action contains any save or export commands, you can set the following options:
- Override Action “Save” Commands
- Saves the processed files in the specified destination folder and not to a location recorded in the action. Click Choose to specify the destination folder.
- Override Action “Export” Commands
- Exports the processed files to the specified destination folder and not to a location recorded in the action. Click Choose to specify the destination folder.
If you select Data Sets for Source, you can set an option for generating filenames when overriding Save and Export commands:
- File + Number
- Generates the filename by taking the original document’s filename, removing any extension, and then appending a three‑digit number corresponding to the data set.
- File + Data Set Name
- Generates the filename by taking the original document’s filename, removing any extension, and then appending an underscore and the name of the data set.
- Data Set Name
- Generates the filename by taking the name of the data set.
You can drag the icons and drop them into Illustrator to import more than one. There is a bug though so you have to deselect all hten slect all adn you can then scale 20%. Since they are nameds in numerical order they will come in that way.
Only problem I see is with 500 images, you will exceeed the max document size.
You could use bridge to make a contact sheet for you. I increased the right value (eg: 6") to get the column to align to the left side rather than center align.
If you need to open the .pdf in Illustrator as a multipage artboard document this script works on mac