Is it legal to sell a game made with free unity under the following circumstances?

If you buy the stuff like music and sounds or images that are royalty free or if you make the images and sounds yourself then it's ok to sell products you make containing that content, you need to check any licensing agreements on those objects and on the related websites you get them from where you download them.

Some things people make and supply themselves and don't care about weither it's re-used commercially or not, sometimes due to lack of availability.

Most the content in Unity3D I would say just use for learning only and build or obtain the neccassary components you need for your game, don't be afraid to unleash your inner creativity.

I know it's overwhelming for most due to the unorganized or unavailable content out their specific to most developers needs, that's one reason I'm starting to like this Unity development concept because it is very organized and does have good information and support to get ball rolling without needing to recreate wheel everytime.

Many TOS and other licensing agreements put on websites these days are not actually supported by the law and some drafted by lawyers are either outdated or don't truelly reflect fully legal means and step over boundaries of what's legal.

Many example TOS agreements give them more power or entitlement than the consumer, and some seek to have controlled rights over even the content you create yourself or usage of something you've already paid for and then attempt to limit access or completely give you nothing in return on your investment and giving refund or credit, in most cases those agreements are null and voided in court and actually can be illegal leading to legal and financial action against those that issuing the agreement. This also happens in changes or modifications to existing agreements. Nobody can give themselves full power or entitlement in that manner even though many businesses will claim to be able to change or modify agreements at any time, it is illegal to change to agreements or contracts once it has been set and agreed too by all parties the first time, dated and signatured, and fully supports the laws in the governing countries and/or states the parties reside, etc... Yet today many businesses step over legal boundaries and due just that and they don't have any concept of what's legal.

Such as patented and copyrighted materials, in order for patent to be legal pertaining to design, you are required by law to fully submit to patent office and it must be researched and approved, just putting a copyright or patent notice on a website is not enough. Every image you download from webrowser by design must first be downloaded to your computer or stream buffered in memory before it can be viewed in browser, so if there was a legal issue with that all copyrights would be broken of every website you visit because you are copying content from every website you visit.

If you go to my website you've already downloaded webpage with text and have a copy on your computer of images I made, so does that mean a copyright protecting those materials would be legal? No, under public submission standards once you upload or submit a pic or information you did that knowing others could see copy and redistribute it. However, the legal issue would come into play only if you made claim to being the sole creator of those materials and content and if a site or content was copied and redistributed without written consent which may or may not also be misleading.

For example, if I had picture of a fence, and you redistributed the picture and said it was your fence and you made it, that would be misleading the public and therefore would not be legal.

No, I'll bet that most of those images from Google are copyrighted. I suggest seeking royalty and license-free material.